Race-neutral spirometry reference equations change the interpretation of tests in South East Asian and Black pediatric patients

RATIONALE: The 2012 Global Lung Function Initiative (GLI) spirometry reference equations rely on race to predict pulmonary function, which may disproportionately affect diagnosis and management of respiratory conditions in certain groups. However, the impacts of newly endorsed race-neutral GLI Global equations have been understudied in pediatric populations. OBJECTIVES: To evaluate differences in percentage and severity of pediatric lung function impairments identified using the race-specific 2012 GLI equations compared to the race-neutral GLI Global equations. METHODS: Retrospective spirometry data for British Columbia Children's Hospital patients aged 5-18 years from August 2022 to June 2024 was interpreted using the race-specific and race-neutral GLI equations. Impairment severity was assessed with forced expiratory volume in 1 second (FEV1) z-scores. FEV1, forced vital capacity (FVC), and FEV1/FVC lower limits of normal were used to classify tests as normal, obstructive, suspected restrictive, or suspected mixed. RESULTS: Spirometry results from 1759 Caucasian, 44 Black, 31 North East Asian, 421 South East Asian, and 691 Other/Mixed individuals were analyzed. Compared to the race-specific, the race-neutral equations identified a mean decrease in FEV1 z-score of 0.77 (95% CI, 0.67-0.86) in the Black population, corresponding to increased impairment severity in 22.7% (95% CI, 11.5%-37.8%) of this group. In contrast, the Caucasian population showed a mean increase in FEV1 z-score of 0.36 (95% CI, 0.35-0.37), with decreased severity observed in 13.5% (95% CI, 11.9%-15.2%). Percentage of suspected restriction increased in Black individuals from 20.5% (95% CI, 9.8%-35.3%) to 43.2% (95% CI, 28.3%-59.0%) and decreased in Caucasian from 14.4% (95% CI, 12.8%-16.2%) to 9.0% (95% CI, 7.7%-10.5%). The South East Asian group experienced the largest increase in mean FEV1/FVC z-score using the race neutral equations, rising by 0.45 (95% CI, 0.44-0.46), which corresponded to a reduction in obstructive impairments from 17.1% (95% CI, 13.6%-21.0%) to 7.8% (95% CI, 5.5%-10.8%). CONCLUSIONS: The race-neutral GLI equations produced the greatest decrease in obstruction in the South East Asian population, while the largest increases in severity and suspected restriction were found in the Black population. The diagnostic and management implications of these changes will require consideration as the race-neutral equations are implemented clinically for pediatric patients.